1. Field of the Invention
The present invention relates, in general, to a method for preparing a water-soluble iron-containing microcapsule by use of fatty acid ester. More specifically, the present invention relates to a method for microencapsulating soluble iron, such as ferric ammonium sulfate, ferrous lactate or ferric ammonium citrate, using polyglycerin monostearate (PGMS) as the fatty acid ester.
2. Description of the Prior Art
Of inorganic components present in very small amounts in the human body, iron is susceptible to extreme deficiency in the body. This is because of poor absorption of iron according to insufficient ingestion of iron-containing foods, rapid growth of the body and blood loss, as well as, in the case of females, exhaustion of the stored iron attributed to pregnancy. In human beings, the times at which iron is apt to be deficient are six-months to four-years-old, adolescence, menacme creating menstrual bleeding, and duration of pregnancy, requiring increased amounts of iron. In particular, iron is liable to be deficient in infants and pregnant women. Generally, iron deficiency results in anemia, a loss of energy, impaired mental functions and faculties, a reduction of resistance to disease and infection, an increase of lead poisoning, and a malformed fetus in the case of iron-deficient pregnant women.
In accordance with recent reports associated with iron deficiency, male students were found to have iron-deficiency ratios in the average range of 10% or less, for example, 16.8% at 14 years, 11.5% at 16 years, and 6.5% at 17-18 years. While female students have iron-deficiency ratios of 31.7% at 14 years, 32.1% at 15 years, 42% at 16 years, 35.8% at 17 years, and 39.3% at 18 years. Schoolgirls have twice or more the ratio of iron deficiency than schoolboys, in all age brackets. Commonly, the female is ill-nourished by the diet, in addition to menstrual bleeding, so that iron is deficient in the body. In addition, serious health problems occur when the female has an iron-deficiency ratio of 30% or higher, after 19 years of age, at which growth is stopped. In infants ingesting breast milk as the principal food, health problems such as a drop of brain development may be caused, due to the low iron content (0.53 mg/l) in milk.
As part of the effort to supply iron to general people, iron processed to various forms is added to foods or medicines. However, when a large amount of iron is added to foods, other problems arise because of very low solubility of iron. That is, if iron is directly added to foods such as milk, oxidation of fat in milk causes milk to be acidified, and disagreeable smells, discoloration and precipitation of iron occur. In addition, for addition of iron to foods, iron in the form of stable salts is used but may decrease bioavailability owing to different properties of foods. Also, iron competes with calcium, phosphorous and other trace ions comprising a very small amount of inorganic components in foods, so that absorption of iron into the body is inhibited. Therefore, a stable and effective method for providing iron to the body is required, without lowering quality of foods and inhibiting bioavailability of iron when iron is added to foods.
Conventionally, methods for increasing iron content in foods have been used to directly add iron to foods. However, in order to alleviate problems of conventional methods, it has been tried to microencapsulate iron and apply it to yogurt, infant formula milk powder, cheese and foods. But such attempts to apply microencapsulated iron to various foods are limited. The microcapsule used in the yogurt and infant formula milk powder, has a size of 75 xcexcm to 100 xcexcm or larger, and thus may be applied to slurry phase such as yogurt, or powder. But, the microcapsule having such particle size is difficult to apply to foods having low viscosity, such as milk and liquid beverages, because the microcapsule with large particle size is easily precipitated, thus causing the value of the commodity to be lowered, and precipitants in the foods are distasteful to consumers. Additionally, in research for applying such microcapsules to cheese, fat in milk is mixed with stearin and emulsifier (sorbitan monostearate) and thus off-flavor attributed to emulsifier occurs. As such, said research suffers from the disadvantages that the size of the prepared microcapsule (5-10 xcexcm) is not suitable to apply to milk or liquid beverages, and off-flavor and precipitation occur, so that such capsule cannot be applied to various foods.
Leading to the present invention, the intensive and thorough research on improvement of conventional microencapsulated iron, carried out by the present inventors aiming to avoid the problems encountered in the prior arts, resulted in the finding that microencapsulated iron prepared according to a method of the present invention is uniformly dispersed when added to milk, thus causing no physical and chemical change of milk during its shelf life (12 days) while having similar taste and color in treated milk to that of untreated milk, without off-taste, off-flavor, and precipitation in treated milk, whereby the same result as with milk can be obtained even though said microencapsulated iron is applied to fruit juice or meats, in which the use of conventional microencapsulated iron is maximized, the quality decrease of foods being prevented, the processes required to prepare emulsion and microcapsules being shortened, and fatty acid ester which is a tasteless and odorless emulsifier is used as a coating agent of iron and thus other emulsifiers need not be used, the diameter of microcapsule being as small as possible and the yield of microcapsules is increased.
Accordingly, it is an object of the present invention to provide a method for microencapsulating iron to the size of 2-5 xcexcm by use of fatty acid ester, wherein a preparation process of microcapsules is shortened and the yield of microcapsules is improved, thus the microcapsules are easily dispersed when added to milk or liquid beverages, and oxidation of fat in milk or meats is prevented and bioavailability of iron in the body is maximized.